Agriculture Reference
In-Depth Information
Figure 2.5
Continuous fruiting annuals as a percentage ofthe common annual
weeds in 14 crops in New York state (data from Bridges,1992).From top to
bottom: spring grain crops (sweet corn grouped with maize grain),spring
vegetable crops (roughly in decreasing order ofcompetitive ability),winter grain
crops.
exponential growth magnifying small differences in seed size, access to nutri-
ents, proximity to crop plants, etc. The extreme skewness in the distribution
of seed production over individuals in most weed populations indicates that
hand, chemical, or mechanical killing of the largest weeds can reduce weed
densities in subsequent crops even if all individuals are not destroyed.
Mechanical methods for attacking the large weeds that emerge through crop
canopies are discussed in Chapter 4.
Most annual weeds produce a few thousand seeds per individual when
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